Background prior art relating to solar inverters and MPPT in general can be found in: EP0780750A; JP2000020150A; US2005/0068012; JP05003678A; GB2415841A; EP0947905A; WO2006/011071; EP1,235,339A; WO2004/006342; DE100 64 039A; US2005/030772; WO96/07130; U.S. Pat. No. 6,657,419; US2004/117676; US2006/232220; WO2004/001942; GB2419968A; U.S. Pat. No. 7,319,313; U.S. Pat. No. 7,450,401; U.S. Pat. No. 7,414,870; U.S. Pat. No. 7,064,967; “Cost-Effective Hundred-Year Life for Single-Phase Inverters and Rectifiers in Solar and LED Lighting Applications Based on Minimum Capacitance Requirements and a Ripple Power Port”, P. T. Kerin and R. S. Balog—technical paper; US2009/0097283; “Long-Lifetime Power Inverter for Photovoltaic AC Modules”, C. Rodriguez and G. A. J. Amaratunga, IEEE Trans IE, 55(7), 2008, p 2593; and US2008/097655.
We have previously described improved techniques for maximum power point tracking (MPPT) for solar invertors (see our UK patent application No. 1004621.7 filed 19 Mar. 2010 and U.S. patent Ser. No. 12/789,154 filed 27 May 2010). It has been recognised that these techniques facilitate the viable use of novel solar photovoltaic system architectures.